Methods for polishing multiple dielectric layers to form replacement metal gate structures include a first chemical mechanical polish step to remove overburden and planarize a top layer to leave a planarized thickness over a gate structure. A second chemical mechanical polish step includes removal of the thickness to expose an underlying covered surface of a dielectric of the gate structure with a slurry configured to polish the top layer and the underlying covered surface substantially equally to accomplish a planar topography. A third chemical mechanical polish step is employed to remove the dielectric of the gate structure and expose a gate conductor.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method for polishing to form replacement metal gate structures, comprising: a first chemical mechanical polish step to remove overburden and planarize a top layer to leave a planarized thickness over a gate structure; a second chemical mechanical polish step including removal of the planarized thickness to expose an underlying covered surface of a dielectric of the gate structure with a slurry configured to polish the top layer and the underlying covered surface substantially equally to accomplish a planar topography; and a third chemical mechanical polish step to remove the dielectric of the gate structure and expose a gate conductor.
A method for fabricating replacement metal gate structures on a semiconductor wafer involves three chemical mechanical polishing (CMP) steps. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer, leaving a specific thickness of that layer over the gate structure. The second CMP removes the remaining top layer thickness, exposing the underlying dielectric material of the gate structure. This second CMP uses a polishing slurry that removes both the top layer and the exposed dielectric at roughly the same rate, ensuring a flat surface. Finally, the third CMP removes the dielectric material, exposing the gate conductor underneath, preparing the structure for replacement with metal.
2. The method as recited in claim 1 , wherein the planarized thickness is between about 300 to about 600 Å.
The method for fabricating replacement metal gate structures, as previously described, specifies the planarized thickness of the top layer after the first chemical mechanical polishing (CMP) step to be between about 300 Angstroms and about 600 Angstroms. This thickness is critical for ensuring uniform polishing in subsequent steps. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer, leaving this specific thickness of that layer over the gate structure.
3. The method as recited in claim 1 , wherein the top layer includes oxide and the underlying covered surface includes nitride and polysilicon and the second chemical mechanical polish step includes a slurry with a oxide:nitride:polysilicon selectivity of about 1:1:1 to about 2:1:1.
The method for fabricating replacement metal gate structures, as previously described, utilizes specific materials and polishing slurry. The top layer consists of oxide, and the underlying covered surface includes nitride and polysilicon. During the second chemical mechanical polishing (CMP) step, a slurry with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon is used. This means the slurry polishes oxide at about the same rate as nitride and polysilicon (or up to twice the rate for oxide). The first CMP removes excess material (overburden) and flattens (planarizes) the top oxide layer.
4. The method as recited in claim 1 , wherein the second chemical mechanical polish step includes a slurry having silica abrasives dispersed in aqueous solution from 0.5 to 30 W %.
The method for fabricating replacement metal gate structures, as previously described, involves a second chemical mechanical polishing (CMP) step using a specific slurry. This slurry contains silica abrasives dispersed in an aqueous (water-based) solution. The concentration of silica abrasives ranges from 0.5 to 30 weight percent (W %). This slurry is used to remove the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
5. The method as recited in claim 4 , wherein the slurry includes organic acid in a range of 0.01 to 30 g/L.
The method for fabricating replacement metal gate structures, as previously described, uses a slurry in the second chemical mechanical polishing (CMP) step that includes an organic acid in a concentration ranging from 0.01 to 30 grams per liter (g/L). This slurry also contains silica abrasives dispersed in aqueous solution from 0.5 to 30 weight percent (W %). This slurry is used to remove the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
6. The method as recited in claim 5 , wherein the slurry includes an acidic pH modulator in a range of 0.01 to 10 g/L.
The method for fabricating replacement metal gate structures, as previously described, specifies that the slurry used in the second chemical mechanical polishing (CMP) step includes an acidic pH modulator in a concentration ranging from 0.01 to 10 grams per liter (g/L). The slurry also contains silica abrasives dispersed in aqueous solution from 0.5 to 30 weight percent (W %) and an organic acid in a range of 0.01 to 30 g/L. This slurry is used to remove the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
7. The method as recited in claim 6 , wherein the slurry includes an alkaline pH modulator in a range of 0 to 15 g/L.
The method for fabricating replacement metal gate structures, as previously described, utilizes a slurry in the second chemical mechanical polishing (CMP) step that includes an alkaline pH modulator in a concentration ranging from 0 to 15 grams per liter (g/L). The slurry also contains silica abrasives dispersed in aqueous solution from 0.5 to 30 weight percent (W %), an organic acid in a range of 0.01 to 30 g/L, and an acidic pH modulator in a range of 0.01 to 10 g/L. This slurry is used to remove the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
8. The method as recited in claim 7 , wherein the slurry includes a pH range from 1 to 11.
The method for fabricating replacement metal gate structures, as previously described, requires the slurry used in the second chemical mechanical polishing (CMP) step to have a pH range from 1 to 11. The slurry also contains silica abrasives dispersed in aqueous solution from 0.5 to 30 weight percent (W %), an organic acid in a range of 0.01 to 30 g/L, an acidic pH modulator in a range of 0.01 to 10 g/L, and an alkaline pH modulator in a range of 0 to 15 g/L. This slurry is used to remove the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
9. The method as recited in claim 1 , wherein the second chemical mechanical polish step includes a slurry having 5 W % of colloidal silica abrasives dispersed in water, 0.5 to 50 g/L of organic acid having two or more carboxylic acid groups, 0.25 to 0.35 g/L of inorganic acid, 0.1 to 1.0 g/L of inorganic base, and a pH in the range of 2-5.
The method for fabricating replacement metal gate structures, as previously described, uses a specific slurry composition for the second chemical mechanical polishing (CMP) step. The slurry consists of 5 weight percent (W %) of colloidal silica abrasives dispersed in water, 0.5 to 50 grams per liter (g/L) of organic acid containing two or more carboxylic acid groups, 0.25 to 0.35 g/L of inorganic acid, 0.1 to 1.0 g/L of inorganic base, and a pH in the range of 2-5. This slurry removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
10. The method as recited in claim 1 , wherein the second chemical mechanical polish step includes a two part slurry with a composition of: a first part having 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator; and a second part having 0.01 to 5 g/L alkaline pH modulator, and 0.01 to 50 g/L acidic pH modulator.
The method for fabricating replacement metal gate structures, as previously described, employs a two-part slurry for the second chemical mechanical polishing (CMP) step. The first part contains 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator. The second part contains 0.01 to 5 g/L alkaline pH modulator, and 0.01 to 50 g/L acidic pH modulator. These two parts are mixed to form the final slurry that removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
11. The method as recited in claim 1 , further comprising supplying a slurry to a polishing table as two components to mix on the polishing table to create a final composition and using the same or different slurry flow rates such that a slurry composition is varied during the polish.
The method for fabricating replacement metal gate structures, as previously described, involves supplying the slurry for the second chemical mechanical polishing (CMP) step as two separate components to a polishing table, where they mix to create the final slurry composition. The flow rates of these two components can be the same or different, allowing for variation in the slurry composition during the polishing process. This enables dynamic control over the polishing rate and selectivity. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer. The second CMP removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The third CMP removes the dielectric material, exposing the gate conductor.
12. The method as recited in claim 1 , wherein the second chemical mechanical polish step includes a two part slurry with a composition of: a first part having 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator; and a second part having 0.5 to 30% silica abrasive slurry, 0.01 to 5 g/L alkaline pH modulator and 0.01 to 50 g/L acidic pH modulator.
The method for fabricating replacement metal gate structures, as previously described, utilizes a two-part slurry for the second chemical mechanical polishing (CMP) step. The first part contains 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator. The second part contains 0.5 to 30% silica abrasive slurry, 0.01 to 5 g/L alkaline pH modulator and 0.01 to 50 g/L acidic pH modulator. These two parts are mixed to form the final slurry that removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer.
13. The method as recited in claim 1 , further comprising wet etching to ensure the top layer is completely removed from the dielectric of the gate structure.
The method for fabricating replacement metal gate structures, as previously described, further includes a wet etching step after the second chemical mechanical polishing (CMP) to ensure the complete removal of the top layer from the dielectric of the gate structure. This wet etching step uses a chemical etchant to remove any remaining portions of the top layer. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer. The second CMP removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The third CMP removes the dielectric material, exposing the gate conductor.
14. The method as recited in claim 1 , wherein the third chemical mechanical polish step includes a slurry capable of a higher polishing rate for the dielectric of the gate structure and lower polishing rates for the top layer and the gate conductor.
The method for fabricating replacement metal gate structures, as previously described, specifies the slurry used in the third chemical mechanical polishing (CMP) step is designed to polish the dielectric of the gate structure at a faster rate compared to the top layer and the gate conductor. This selective polishing ensures the dielectric is removed efficiently without damaging the other layers. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer. The second CMP removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure. The third CMP removes the dielectric material, exposing the gate conductor.
15. The method as recited in claim 1 , wherein the third chemical mechanical polish step includes a slurry composition of: 5 to 10 W % of colloidal silica abrasive, 0.1 to 10 g/L of inorganic acid, and a pH in the range of 2 to 6.
The method for fabricating replacement metal gate structures, as previously described, specifies a specific slurry composition for the third chemical mechanical polishing (CMP) step. This slurry contains 5 to 10 weight percent (W %) of colloidal silica abrasive, 0.1 to 10 grams per liter (g/L) of inorganic acid, and has a pH in the range of 2 to 6. This slurry composition is used to remove the dielectric material, exposing the gate conductor. The first CMP removes excess material (overburden) and flattens (planarizes) the top layer. The second CMP removes the planarized thickness of the top layer, exposing the underlying dielectric material of the gate structure.
16. A method for polishing replacement metal gate structures to planarize oxide layers and expose underlying nitride and polysilicon covered areas, comprising: a first chemical mechanical polish step to remove overburden and planarize oxide layers leaving 300 to 600 Å of oxide remaining; a second chemical mechanical polish step including removal of the oxide layers and exposing underlying nitride and polysilicon covered surfaces with an oxide:nitride:polysilicon selectivity of about 1:1:1 to about 2:1:1 to provide planar topography; a third chemical mechanical polish step to remove the nitride layers and expose the polysilicon layers; and replacing at least a portion of the polysilicon layer with a metal layer to form the metal gate structure.
A method for polishing replacement metal gate structures involves three chemical mechanical polishing (CMP) steps to planarize oxide layers and expose underlying nitride and polysilicon covered areas. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers. Finally, at least a portion of the polysilicon layer is replaced with a metal layer to form the metal gate structure.
17. The method as recited in claim 16 , wherein the second chemical mechanical polish step includes a slurry including silica abrasives dispersed in aqueous solution from 0.5 to 30 W %, organic acid in a range of 0.01 to 30 g/L, an acidic pH modulator in a range of 0.01 to 10 g/L, an alkaline pH modulator in a range of 0 to 15 g/L, and a pH range from 1 to 11.
The method for fabricating replacement metal gate structures, as previously described, utilizes a specific slurry composition for the second chemical mechanical polishing (CMP) step. This slurry contains silica abrasives dispersed in an aqueous solution from 0.5 to 30 weight percent (W %), organic acid in a range of 0.01 to 30 grams per liter (g/L), an acidic pH modulator in a range of 0.01 to 10 g/L, an alkaline pH modulator in a range of 0 to 15 g/L, and a pH range from 1 to 11. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers.
18. The method as recited in claim 16 , wherein the second chemical mechanical polish step includes a slurry having 5 W % of colloidal silica abrasives dispersed in water, 0.5 to 50 g/L of organic acid having two or more carboxylic acid groups, 0.25 to 0.35 g/L of inorganic acid, 0.1 to 1.0 g/L of inorganic base, a pH in the range of 2-5.
The method for fabricating replacement metal gate structures, as previously described, specifies a particular slurry for the second chemical mechanical polishing (CMP) step. This slurry has 5 weight percent (W %) of colloidal silica abrasives dispersed in water, 0.5 to 50 grams per liter (g/L) of organic acid having two or more carboxylic acid groups, 0.25 to 0.35 g/L of inorganic acid, 0.1 to 1.0 g/L of inorganic base, and a pH in the range of 2-5. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers.
19. The method as recited in claim 16 , wherein the second chemical mechanical polish step includes a two part slurry with a composition of: a first part having 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator; and a second part having 0.01 to 5 g/L alkaline pH modulator, and 0.01 to 50 g/L acidic pH modulator.
In semiconductor manufacturing, chemical mechanical polishing (CMP) is used to planarize surfaces, but achieving precise material removal rates and selectivity between different layers remains challenging. This invention addresses these issues by optimizing the slurry composition for a two-step CMP process. The method involves a second CMP step using a two-part slurry system. The first part of the slurry contains 0.5 to 30% silica abrasive, 0.5 to 50 g/L of an organic acid, and 0.01 to 5 g/L of an acidic pH modulator. The second part includes 0.01 to 5 g/L of an alkaline pH modulator and 0.01 to 50 g/L of an acidic pH modulator. The dual-slurry approach allows for controlled pH adjustment and enhanced material removal selectivity, improving polishing efficiency and uniformity. The acidic and alkaline modulators in each part enable fine-tuning of the polishing process, ensuring consistent performance across different semiconductor materials. This method is particularly useful in advanced semiconductor fabrication where precise layer removal and surface planarity are critical.
20. The method as recited in claim 16 , further comprising supplying a slurry to a polishing table as two components to mix on the polishing table to create a final composition and using the same or different slurry flow rates such that a slurry composition is varied during the polish.
The method for fabricating replacement metal gate structures, as previously described, involves supplying the slurry for the second chemical mechanical polishing (CMP) step as two separate components to a polishing table, where they mix to create the final slurry composition. The flow rates of these two components can be the same or different, allowing for variation in the slurry composition during the polishing process. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers. Finally, at least a portion of the polysilicon layer is replaced with a metal layer to form the metal gate structure.
21. The method as recited in claim 16 , wherein the second chemical mechanical polish step includes a two part slurry with a composition of: a first part having 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator; and a second part having 0.5 to 30% silica abrasive slurry, 0.01 to 5 g/L alkaline pH modulator and 0.01 to 50 g/L acidic pH modulator.
The method for fabricating replacement metal gate structures, as previously described, employs a two-part slurry for the second chemical mechanical polishing (CMP) step. The first part contains 0.5 to 30% silica abrasive slurry, 0.5 to 50 g/L organic acid, and 0.01 to 5 g/L acidic pH modulator. The second part contains 0.5 to 30% silica abrasive slurry, 0.01 to 5 g/L alkaline pH modulator and 0.01 to 50 g/L acidic pH modulator. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers.
22. The method as recited in claim 16 , further comprising wet etching to ensure the oxide layer is completely removed from the nitride of a gate structure.
The method for fabricating replacement metal gate structures, as previously described, further comprises a wet etching step to ensure the oxide layer is completely removed from the nitride of the gate structure after the second chemical mechanical polishing (CMP) step. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers.
23. The method as recited in claim 16 , wherein the third chemical mechanical polish step includes a slurry capable of a higher polishing rate for the nitride of a gate structure and lower polishing rates for oxide and polysilicon.
The method for fabricating replacement metal gate structures, as previously described, specifies that the third chemical mechanical polishing (CMP) step utilizes a slurry that polishes the nitride of the gate structure at a higher rate compared to the oxide and polysilicon layers. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers.
24. The method as recited in claim 16 , wherein the third chemical mechanical polish step includes a slurry composition of: 5 to 10 W % of colloidal silica abrasive, 0.1 to 10 g/L of inorganic acid, and a pH in the range of 2 to 6.
The method for fabricating replacement metal gate structures, as previously described, requires the slurry used in the third chemical mechanical polishing (CMP) step to have a specific composition. The slurry comprises 5 to 10 weight percent (W %) of colloidal silica abrasive, 0.1 to 10 grams per liter (g/L) of inorganic acid, and a pH in the range of 2 to 6. The first CMP removes excess material and planarizes the oxide layers, leaving 300 to 600 Angstroms of oxide remaining. The second CMP removes the remaining oxide layers and exposes the underlying nitride and polysilicon covered surfaces with a polishing selectivity ratio of approximately 1:1:1 to 2:1:1 for oxide:nitride:polysilicon to create a flat surface. The third CMP removes the nitride layers and exposes the polysilicon layers.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 25, 2011
August 13, 2013
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.